Light source shielding means for fluorescent luminaire



Aug. 25, 1953 R. AABBERLY 2,650,293

LIGHT SOURCE SHIELDING MEANS FOR FLUORESCENT LUMINAIRE Filed Jan. 28, 1950 2 Sheets-Shet 2 1117 p 2 x32 x x |NVENTOR Patented Aug. 25, 1953 OFFICE 2,650,293 LIGHT SOURCE SHIELDING MEANS FOR FLUORESCENT LUMINAIR Nicholas Rippen Aabberly, New York, N. Y. Application January 28, 1950, Serial No. 141,095

This invention is in the class of elongated fixtures adapted to hold one or more elongated, straight electric discharge lamps extending in the general direction of the long fixture axis. Theiixturehas, in transverse sectional aspects thereof thruout the greater part of thefixture length, substantially constant peripheral dimension and a substantially constant form bilaterally symmetrical about the luminaire plane of symmetry, which is vertical when the fixture is ailxed to a ceiling, beam or other structural elee ment having a substantially horizontal surface. The invention is equally useful when incorporated in luminaires des ned for attachment to vertical surfaces.

The invention is particularly useful in luminaires arranged in end to end relation constituting "ribbons" or lines of light. The invention is useful in fixtures that adjointhe ceiling and in those that are suspended below it, as mentioned.

The lamps may be of the fluorescent type, or of the cold cathode type. Herein, the expression, light source, refers to a single lamp or to a group of adjacent and parallel lamps.

The salient object and advantage of the invention consists in the provision of luminaire ends that, in the case of newly installed lamps, have an average all-angular coefiicient of light transmission higher than that of the intervening main part of the luminaire, or in the provision of the described relationship but confined to a single side of the luminaire, the difference in the coeiilcients being such that, when the lamp ends havedarkene'd with age, said coefllcient will be fairly uniform thruout the luminaire or side.

As asimple and typical embodiment of the invention, one having a louver iloor assembly and two lateral sides, each lateral side consisting of a combination of translucent, longitudinally extending platelike material and upwardly 11 Claims. (Cl. 24051.11)

extending integral extensions of the transverse louver elements in the floor side, has been selected for description herein and illustration in the accompanyin v drawings, in which Figure 1 is a side elevational view of one complete embodiment positioned between two fragmentarilyrepresented similar embodiments, all depicted schematically and on a. greatly reduced scale, I

Figure 2 is an end view of the same, the aspect being indicated by arrow 2 in Figure 1, the scale being one-half of actual size,

Figure 3 is a schematic presentation or certain louver arrangements to showtheir relation to each other and the relation of each tothe light source, the aspect corresponding to that of Figure 1.

of'Fig. 2 without perspective,- and Figure 5 is a fragmentary view of one of the compound louvers in Figure 2.

In Figure l, the complete central embodiment and each or the two adjoining fragmentary embodiments are indicated by. III. In each, the supporting body or mainframe consists of the longitudinal frame IIA, .I I3, and the endirames I2 rigidly afllxed thereto. Frame IIA, IIB comprises the wiring channel, and also a housing for the ballasts and starters, the web oi the channel being indicated by HE and each channel leg by IIA. 'Each end frame I2 mounts the upper 5-lamp lampholder I I, and the lower lampholder II. Each frame If consists of a shallow channel with narrow secondary flanges. The rigid connection between frame II A, H3 and each frame I2 is provided bybracket IIA, I513, IIC, the two legs ISA, of the bracket being spotwelded to the two legs of the channel, HA. The bracket web I5B, a central integral flap I50, and an extension of web I5B, are respectively spotwelded to the web or frame I! and to the end portion of the channel web I IB. In the webs of the bracket and the end frame are two alined holes bushed by the grommet ii to accommodate electrical conductors. A snap-in closure, closing the otherwise open bottom of channel HA, I I3, i indicated by 21. The lampholders, schematically depicted, may be of one-pin or two-pin type.

parallel dimension, and two upwardly extending I integral louver elements I IB, mutually transversely opposed, on opposite sides of the plane of symmetry. Amxed to the frame II are two modified compound louvers 22A, 12B, each including a minor louver element 22A and two integral upwardly extending louver elements 223. Louver elements 223 have dimensions and a form like those of louver elements IIB. The

dimension of each minor louver element 22A Figure 4 is a cross-sectlonalfview on .line 4-4 in the plane of symmetry is exceeded by that of each major louver element 2IA. Also constituting a part of the louver assembly containing louver elements HA and 22A are six pairs of simple louvers or minor louver elements 23, the dimension thereof being exceeded by that of said major louver elements and, in this case,

being equal to that of minor louver elements 22A. The lower edge of all the transverse louvers, as seen in the drawings and particularly in Fig. 3, are in substantial alignment but the dimensions of the major louvers are so much greater than the dimensions of the major louvers are so much greater than the dimension of the minor louvers that the upwardly disposed edges of the major louvers extend well beyond the upwardly disposed edges of the minor louvers. At each end of said louver assembly there are four spotwelded U-brackets 24 related to one another and to the various louver elements in a manner whereby a major louver element and a respective minor louver element 22A jointly support three of the six pairs of minor louvers 23.

The lower lamp 25 is held by lower lampholder l4 and the five upper lamps 26 constituting the upper light source are held by lampholders Hi.

In Figure 3, the vertical dotted lines indicate the averag dimensions of the louver elements.

both major and minor, and particularly the relative height thereof. They are so spaced as to condition longitudinal cut-oil angles of thirtytwo degrees from the horizontal, thruout the luminaire length, this cut-off angle being indicated by the two pairs of oblique dash lines in the view. Approximately eighteen inches of joint luminaire length traverse each juncture. In this length the light rays fall on the minor louver elements much more than would be the case should each two minor louver elements 22A, adjacent each juncture, be the same average height as that of the major louver elements. The enhanced lighting effect is prominent particularly in the case of those two pairs of simple louvers 23 between each two mutually adjacent louver elements 22A and of the two junctum-confronting surfaces of the louver elements 22A. This effect can be augmented still more by making the endmost simple louver at each end of translucent plastic instead of metal, while retaining the latter for the remainder of the transverse louvers.

Refer to Figure 2. The transverse cut-off angle is fixed at forty-five degrees. It is indicated, respectively for the upper and the lower light source, by the planes 28A, 28B and 29A, 293. For the underneath observer, each pair of such planes condition an angle of visibility of ninety degrees of each light source. Depending on the transverse dimensions desired and on the purpose of the particular type of luminaire, especially with respect to the amount of brightness required, said angle of visibility may be as much as one-hundred-forty degrees.

7 Laterally shielding the lower light source 25 is the lower platelike, longitudinally extending lower shielding means 30A, 30B, "0, consisting of one or more translucent plastic sheets. Laterally shielding the upper light source 26 is the upper platelike. longitudinally extending upper shielding means 3|A, 3IB; 3|C, consisting of one or more translucent plastic sheets. The two respective mean planes of the two lower shielding means, indicated by 30D, form an angle of one-hundred-fifty degrees with all upwardly exthirty degrees,

tending apex. The two respective mean planes of th two upper shielding means, indicated by 3ID, form an angle of one hundred-fifty degrees with a downwardly extending apex. The longitudinal margins of each shielding means is provided with a plurality of shallow notches, which are engaged by a corresponding plurality of correspondingly small portions of the inner margins of said upwardly extending louver elements at the positions indicated by X. By this relationship, the shielding means, which are flat in th non-installed state and resiliently sprung into slightly arcuated form in the installed state, are firmly but detachably retained by the upwardly extending louver elements.

There is less light at the junction of a pair of fixtures arranged in end to end relation than there is along the inwardly spaced portion of the light source. This becomes particularly marked as the lamps grow old and emit less illumination from the end zones thereof. For the purpose of compensating for this difference, the end panels 3IA and 3IC of each luminaire unit may be somewhat more translucent than the intermediate panels 31B.

A platelike translucent element when not provided with prismatic surfaces or the like transmits a maximum of light rays at right angles to the surfaces. Because of this, the arrows 32, 32 and 33, 33, indicate respectively angles of incidence of onehundred-flfty degrees (derived from the angular positions of the planes 30D and MD) along which the brightest rays pass from said light sources thru the shielding means. Such rays, because they fall on the most distant areas below and on the ceiling, are more effective than the distance of the light sources therefrom would otherwise permit; by this expedient, an appreciable amount of compensation is attained for loss of luminosity due to greater distance from the light sources, thereby attaining, a greater measure of somewhat uniform light respecting area served by the luminaire. 'Respecting the planes 31D andAflD, it would seem that angleswith upwardly and downwardly extending apices measuring less than seventy-five degrees would be more or less acceptable. However, conditions permitting, it would seem best to approach as closely aspossiblethe small angle fixed in the vizggiforlthe foregoing, namely,

minaires mountedadjacent the ceiling; this has of course reference particularly-to the upper light source and upper shielding means.

Numeral 34 indicates mounting plates, also referred to as contributory mounting means,

' which either engage with other mounting plates frame member, two lampholders respectively at the two ends of the frame member and adapted to jointly hold an elongated straight electric discharge lamp, and a set of plate-like, longitudinally extending, translucent, shielding" panels disposed in end-to-end relation in said frame and in laterally spaced relation to said lamp, the set including two end panels and at least one intervening panel longer than the comespeeially in the cases: Iii-TI bined lengths of the end panels and having a lower light-transmission coeilicient than that of the end panels.

2. In an elongated luminaire, a longitudinal frame member, two lampholders respectively at the two ends of the frame member and adapted and minor louver elements being underneath the lamp, the vertical dimension of each major louver element exceeding that of each minor louver element.

3. In an elongated luminaire, a longitudinal upwardly extending portion which is outside of and supports the shielding panel along two mutually spaced relatively small edge portions of the louver element, there being between said small edge portions a relatively large edge por- 'tion of the louver element that is spaced from the shielding panel. '7. The combination defined in claim 6 wherein the shielding panel comprises end sections and frame member, two lampholders respectively at a the two ends of the frame member and adapted to jointly hold an elongated, straight, electric discharge lamp, two relatively small pluralities of transverse minor louver elements respectively adjacent the two luminaire ends, and a relatively large plurality of transverse major louver elements between said two pluralities, each of said major and minor louver elements being underneath the lamp, the vertical dimension of each major louver element exceeding'that of each minor louver element, and the spacing between each two successive major louver elements exceeding the spacing between each two successive minor louver elements.

4. In an elongated luminaire, a longitudinal frame member, two lampholders respectively at the two ends of the frame member and adapted to jointly hold an elongated, straight electric discharge lamp, spaced, transverse minor louver elements respectively adjacent the two luminaire ends, a plurality of spaced, transverse, major louver elements between said minor louver elements and in a plurality exceeding that of the minor elements, each of said major and minor louver elements being underneath the lamp, the vertical dimension of each major louver element exceeding that of each minor louver element, and a set of plate-like, longitudinally extending, translucent shielding panels disposed in end-to-end relation in said frame member and in laterally spaced relation to said lamp, the set including two end panels and at least one intervening panel longer than said end panels and having a lower light-transmission coefficient than that of the end panels.

5. The invention defined in claim 2 in which the spacing between each two successive major louver elements exceeds the spacing between 5 each two successive minor louver elements.

6. In an elongated luminaire, a longitudinal frame member, two lampholders respectively at the two ends of the frame member and adapted to hold an elongated, straight electric discharge lamp extending longitudinally of the luminaire, at least one plate-like longitudinally extending, translucent shielding panel disposed in said frame member in laterally spaced relation to the lamp, a plurality'of, transverse louver elements,

each of at least most thereof comprising a transverse portion under said lamp and an integral at least two longitudinally an intermediate section, and wherein the intermediate section has a lower light-transmitting coefficient than that of the end sections.

8. The combination defined in claim 6 wherein the transverse louver elements comprise: at least two longitudinally spaced, transverse, minor louver elements respectively adjacent the two luminaire ends, and a plurality of spaced, transverse, major louver elements between said minor louver elements and in a plurality exceeding a that of the minor louver elements, each of said major and minor louver elements being underneath the lamp, and the vertical dimension of each major louver element being greater than that of each minor louver element. 9. The combination defined in claim 6 wherein the transverse louver elements comprise interspaced major and minor louvers, the vertical dimension of each major louver element exceeding that of each minor louver element, and the spacing between each two successive major louver elements exceeding the spacing between each two successive minor louver elements.

10. The combination defined inclaim 6 wherein the-shielding panel includes two end sections and at least one intervening section which has a light-transmission coemcient greater than that of the end sections, and wherein said transverse louvers include at least two longitudinally spaced, transverse, minor louver elements respectively adjacent the two luminaire ends, and a plurality of spaced, transverse, major louver elements between said minor louver elements and in a plurality exceeding that of the minor elements, each of said major and minor louver elements being underneath the lamp, and the vertical dimension of each major louver element exceeding that of each minor louver element. 11. In an elongated luminaire, a longitudinal frame member, two lampholders respectively at the two ends of the frame member and adapted to jointly hold an elongated, straight, electric discharge lamp, two relatively small pluralities References Cited in the flleof this patent UNITED STATES PATENTS Number Name Date D. 120,544 Carter, Jr May 14, 1940 2,314,520 Schumaker Mar. 23, 1943 2,436,635 De Bishop, Jr. Feb. 24, 1948 

